1. Field of the Invention
The present invention relates to a gas sensor.
2. Description of the Related Art
There has hitherto been known a gas sensor that detects the concentration of a predetermined gas, such as NOx, in a measurement target gas, for example, exhaust gas from an automobile. For example, a gas sensor described in PTL 1 includes cylindrical body formed of metal, a detection element (sensor element) disposed within the cylindrical body to detect the gas concentration, and lead wires having electrical continuity to the sensor element and extending outward from the cylindrical body. The gas sensor described in PTL 1 further includes a tube surrounding the lead wires, a cover member, and a clamp member.
FIG. 11 is an explanatory view of an end portion of such a gas sensor 300 of the related art. The gas sensor 300 includes an outer cylinder 346 within which an unillustrated sensor element is disposed, lead wires 348 extending outward (upward in FIG. 11) through an opening at an upper end of the outer cylinder 346, and a tube 370 surrounding the lead wires 348. The gas sensor 300 further includes a cover member 390 that covers an upper side of the outer cylinder and a lower side of the tube 370 from the periphery, and a clamp member 380 that clamps a portion of the cover member 390 covering the upper side of the outer cylinder 346 from the outside. At an upper side of the cover member 390, a contact portion 392 is provided to be in contact with an outer peripheral surface of the tube 370 within the cover member 390. In the gas sensor 300, the existence of the cover member 390 restricts water from entering the sensor from the opening at the upper end of the outer cylinder 346.